2015-10-16

HABE Greek Adventure (2)

Today I had the chance to test DL-fldigi with a real balloon downlink, using the weak signal from HABE. I used an Icom IC-7100 radio connected via USB to a PC running Windows XP and DL-fldigi version 3.21.50. The antenna is a tribander vertical (6m, 2m, 70 cm) with a 15 m RG-213 transmission line.

Screen capture of FL-digi in action

I understand that the balloon trackers transmitted telemetry using LPD devices at a power of only 10 mW. Modulation was FSK (nominally 425 and 850 Hz shift) with ASCII encoding. Shortly after lift-off, FL-digi managed to decode a number of packets on 434.650 MHz and 434.200 MHz and upload them to the HAB tracking server, before the balloons drifted to the north, behind Mt Parnis.

I would like to see in the future some experimental beacon with GPS telemetry using the FL-digi specific format, which would help us fine tune our receiving systems.